The invention relates to methods and apparatus for making channel letters for commercial signs, and more particularly to apparatus and methods for reducing the cost and labor involved in making channel letters by providing snap connectors for attachment and removal of plastic letter faces from the metal channel sides of the letters, and by providing snap connectors for attachment and removal of the letter backs.
Channel letters are known to those skilled in the art of making commercial signs as the most expensive form of lettering, and are generally also regarded as the most attractive form of sign lettering. Briefly, channel letters usually include a wood back having the shape of the letter to be formed. Electrical lighting fixtures, such as neon tubing and mounting brackets, are attached to the wood letter back. Metal channel siding, frequently formed of aluminum with a painted or otherwise finished exterior surface, is attached to and sealed to the letter back, giving depth to the letter to be formed. Typically, a colored, transluscent plastic letter face is attached to the front edge portion of the channel side material.
The commercial sign-making industry is a large, labor intensive, multi-million dollar international industry. Although there are several major competitors in the business of supplying the channel siding material usually used in making channel letters, including the Heath Northwest, Inc. Company of Yakima, Wash., with its patented CHANNELUME channel letter fabrication technique, and the Let-R-Edge Company of Hayward, Calif., and a few others who have made innovations in this field, the industry of making channel letters still remains highly labor intensive. U.S. Pat. No. 3,414,305 is generally indicative of the state of the art, as is the CHANNELUME technical brochure entitled "Channelume - An Exciting New Concept in Technical Letter Fabrication" published by Heath Northwest, Inc., and incorporated by reference herein.
Generally, the standard prior manufacturing procedures involve attaching aluminum clad marine plywood referred to as "armored plywood" to the plastic letter facing material, and then attaching the letter "layout pattern" to the other surface of the plastic letter facing material, simultaneously cutting out the letter backs and letter faces with a bandsaw, then using various laborious techniques to bend the metal channel siding material (such as "Channelume or Let-R-Edge" material) to conform to the desired letter shape, using various tools such as a CHANNELUME break devices or a LET R-EDGE break device. Various roller devices, pegboard, and wedge and peg techniques are used to hold and maintain the letter back material, the channel side material, and the letter faces in proper alignment while the channel siding material is glued and/or attached to the letter backing material. The procedures for marking and bending the prior metal channel siding material and attaching it to the letter back and the letter face are especially laborious. Yet, no practical technique is yet known for significantly reducing the high amount of labor required for this phase of conventional channel letter construction techniques.
Furthermore, even after conventional channel letters have been installed, they occasionally require maintenance. For example, it is occasionally necessary to replace defective neon lighting elements inside the channel letters. When such maintenance is required, the procedure for removing the letter face and channel side to achieve access to the internal lighting components of the channel letter lighting system or to clean the interior surface of the transluscent letter face is quite laborious. Furthermore, some of the prior materials used for plastic edging and channel siding are subject to gradual deterioration by sunlight. Such deterioration leads to cracks and openings which allow dust to enter into the interior of the sign, sometimes reducing the amount of light that can pass through the plastic letter facings when layers of dust build up on the inner surfaces of letter faces.
It would be highly desirable to be able to use unbreakable plastic material, such as LEXAN, for letter faces for signs that are subject to destructive forces, such as vandalism. Unfortunately, there are no readily available glue substances that are capable of reliably attaching presently available "unbreakable" plastic materials to present available letter edge materials, such as BUTYRATE. Similarly, it would be highly desirable to be able to use "second side painted" plastic letter faces. "Second side" painted letter faces are clear plastic letter faces with the inner face spray painted. This can be advantageous because there are many more shades of paint available than there are shades of tinted plastic material that is suitable for making letter faces.
Although the technique for making channel letters described in the parent application results in a great improvement over prior techniques, further development of the technique has resulted in significant improvements which are the subject of the present application.